a) Field of the Invention
The present invention concerns headphones for connection to an external active noise compensation device and an adaptor unit for connection between an external active noise compensation device and headphones.
b) Description of the Related Art
Headphones with active noise compensation have long been known. In that respect the corresponding electronics for active noise compensation can either be arranged on the headphones or can be in the form of an external unit. External noise compensation units are known for example from aircraft where noise compensation headphones are used in what is referred to as the in-flight entertainment system. Typically, headphones of that kind have a microphone in the region in the proximity of the ear, which serves to detect the interference noise and feed it to the electronics for active noise compensation. Such solutions however frequently only represent proprietary solutions so that the headphones required cannot readily be interchanged with those from another manufacturer.
WO 2004/002383 discloses a noise compensation system and corresponding headphones. The headphones have a microphone for active noise compensation and a filter network which serves to adapt the response characteristic of the microphone to a standardised impedance or response curve.
DE 693 17 827 T2 discloses headphones with an active noise compensation unit and a filter which selectively reduces the level of the high frequency component of the output signal of the microphone in order in that way to reduce the level of the low frequency component of the external noise by the output signal of the electroacoustic transducer.
Attention is further directed to DE 198 18 925 A1, DE 698 27 245 T2, US No 2003/0228019 A1 and U.S. Pat. No. 5,604,813 as general state of the art.